Toques finais

main.dart

mainAxisAlignment: MainAxisAlignment.center,
   children: <Widget>[
      Text('Configurando um SMTP server: $_text',),
          ],
        ),
      ),
floatingActionButton: FloatingActionButton(
    onPressed: _sendEmail,
    tooltip: 'Send email',
    child: Icon(Icons.email),
  ), // This trailing comma makes auto-formatting nicer for build methods.
);